Ultrasonic thickness gauge display value distortion phenomenon and causes
Ultrasonic thickness gauge in practical applications, especially in the service equipment monitoring, if the value of the distortion, deviation from the actual thickness of the phenomenon, the result caused by the pipeline (equipment) hidden danger exists, that is, based on the wrong data to replace the pipe fittings, resulting in a large amount of material waste. According to several years of ultrasonic thickness measurement tracking use, will show the value of the phenomenon of distortion and the reasons are analysed as follows:
1, no display value display or display value flashing unstable reason analysis: this phenomenon in the field equipment and pipeline testing from time to time, after a large number of phenomena and data analysis, summarise the reasons are as follows:
(1) the surface roughness of the workpiece is too large, resulting in poor coupling between the probe and the contact surface, the reflection of the echo is low, or even can not receive the echo signal. Most of the in-service equipment and pipelines are surface corrosion, and the coupling effect is extremely poor.
(2) The radius of curvature of the workpiece is too small, especially when measuring the thickness of small-diameter pipe, because the commonly used probe surface for the plane, and the curved surface contact for the point contact or line contact, the sound intensity of the transmission rate is low (poor coupling).
(3) The detection surface and the bottom surface is not parallel, the acoustic wave encounters the bottom surface scattering, the probe can not accept the bottom wave signal.
(4) castings, austenitic steel due to uneven organisation or coarse grain, ultrasonic waves in which the passage of serious scattering attenuation, the scattered ultrasonic waves along the complex path propagation, it is possible to make the echo annihilation, resulting in non-display.
